1. Field of the Invention
This invention relates to a process for producing a plasma polymerized film by utilizing low temperature plasma, particularly to a process for producing a plasma polymerized film by pulse discharging.
2. Description of the Prior Art
In use, magnetic tapes, magnetic discs, and the like are placed in a sliding relationship with structural elements, mechanical members, and the like, and the surfaces in sliding contact require lubricity with a small coefficient of friction.
One of the methods known in the art for improving the lubricity of such a sliding surface is to coat the sliding surface with an organic lubricant comprising a fatty acid, and it has been utilized for magnetic tapes, magnetic discs, etc. However, this method has drawbacks in that the lubricant cannot easily be applied uniformly on the sliding surface, the effect may differ depending on the material of the surface to be coated and therefore no satisfactory lubricity can necessarily be obtained, the durability of lubricity is poor because the lubricant is lost gradually by repeated use, and that it has no heat resistance and therefore cannot be used at high temperatures. In addition, it is not applicable for precision machines such as watches and robots. Another method for improvement of lubricity is the method in which the sliding surface is coated with inorganic powder such as graphite powder, molybdenum sulfide powder, lead oxide, calcium fluoride, etc. This method has been utilized for mechanical elements such as gears, bearings, etc. However, this method also involves the same drawbacks as the above organic lubricant. Still another method known in the art is to form a solid lubricating film composed of, for example, polytetrafluoroethylene on the sliding surface and it has been used for sliding surfaces for which chemical resistance is required and sliding surfaces for which heat resistance is required. However, since the lubricating film which can be formed is considerably thick on the order of several tens microns or more, it has the drawback of being not applicable for the bearings, gears, and other such parts of precision machines, video heads, magnetic tapes, magnetic discs and others.